Mechanical manipulator for surgical instruments

ABSTRACT

A novel mechanical system, based on a new cable driven mechanical transmission, able to provide sufficient dexterity, stiffness, speed, precision and payload capacity to actuate multi-DOF micro-manipulators. Besides the possibility of being used in several articulated surgical instruments and robotic systems for surgery or other applications involving remote manipulation, it enables the design of a novel fully mechanical surgical instrument, which offer the advantages of conventional laparoscopy (low cost, tactile feedback, high payload capacity) combined with the advantages of single port surgery (single incision, scarless surgery, navigation through several quadrants of the abdominal cavity) and robotic surgery (greater degrees of freedom, short learning curve, high stiffness, high precision, increased intuition). The unique design of the proposed system provides an intuitive user interface to achieve such enhanced manoeuvrability, allowing each joint of a teleoperated slave system to be driven by controlling the position of a mechanically connected master unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims the benefit of European patent application No10187088.9 and No 10187097.0, both filed on Oct. 11, 2010, the entiredisclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of remotely actuatedmechanisms and devices for use in surgical procedures within theabdominal cavity, using reduced incisions in the abdominal wall.

BACKGROUND OF THE INVENTION

A major progress in abdominal surgery has occurred during the lastdecades with the introduction of laparoscopic and minimally invasivetechniques. These innovative procedures focused much attention due totheir several advantages: smaller abdominal incisions needed, resultingin faster recovery of the patient, improved cosmetics, and shorter stayin the hospital. The safety, efficiency and cost-effectiveness oflaparoscopic surgery have subsequently been demonstrated in clinicaltrials for many routine abdominal operations. However, from thesurgeon's point of view, there are still many difficulties in learningand performing such procedures with current laparoscopic equipment,which is non-ergonomic, non-intuitive and missing in adequate stiffness,precision and force feedback.

In order to overcome the disadvantages of traditional minimally invasivesurgery (MIS), robot technology has been introduced into the operationroom. Although a wide range of diagnostic and therapeutic roboticdevices have been developed, the only commercial systems that havealready been used in human surgery are the do Vinci System, by IntuitiveSurgical, [Guthart2000], and ZEUS, by Computer Motion. Following thefusion between the two companies, the ZEUS robot is no longer produced.The major advantages of these robotic systems are related with theadditional degrees of freedom available to the surgeon that allows morecomplex movements in a limited space, with an increased stiffness. Thisincreased mobility and stiffness has led to short learning curves evenfor non-laparoscopic surgeons. A major disadvantage of these systems isthe high cost of acquisition and maintenance which are actually notaffordable for the majority of surgical departments worldwide. Anotherdrawback of these systems is related with the fact that current surgicalrobots are voluminous, competing for precious space within the operatingroom environment and significantly increasing preparation time. Accessto the patient is thus impaired and this raises safety concerns. Inaddition, although robotic systems offer excellent vision and precisetissue manipulation within a defined area, they are limited inoperations involving more than one quadrant of the abdomen. Since manygastrointestinal operations involve operating in at least two abdominalquadrants, the repeated disconnection and movement of the robotsincrease significantly the duration of the surgical procedure.

Despite various existing interesting systems and after several years ofsurgical instrumentation research, surgical robotics is still only atthe very beginning of a very promising large scale development. One ofthe major open drawbacks is related to the fact that current roboticinstruments are still too bulky and have insufficient dexterity forcomplex surgical procedures.

Further weaknesses of these systems are related with the stiffness,precision and payload capacity of the micro-manipulator units. A largenumber of conventional and robotic manipulators have been developed(Taylor1999, Cavusoglu1999, Mitsuishi2003, Mayer2004, Guthart2000,Tavakoli2003, Seibold2005, Das1997, Dachs2006, Abbott2007, Ikuta2003,Nakamura2000, Yamashita2005, Arata2005, Salle2004, Kobayashi2002,Dario2000, Peirs2003, Simaan2004, Ikuta2003, Focacci2007, Ishii2007) buttheir size, dexterity, stiffness, precision and payload capacity are notcompletely fulfilling the needs for MIS. In some cases, theseinsufficiencies lead to increased operative time or impreciseperformance of several surgical tasks.

Other prior art documents include the following publications: US2005/0096502, US 2009/0247821, GB 969,899, JP 2008-104620, U.S. Pat. No.6,197,017, US 2002/0049367, US 2003/0208186, US 2005/0240078, US2006/0183975, US 2007/0299387, EP 0 595 291, U.S. Pat. No. 6,233,504, US2004/0236316, US 2004/0253079, US 2008/0058776, US 2008/0314181, US2009/0198253, WO 03/067341, WO 2004/052171, WO 2005/046500, WO2007/133065, WO 2008/130235, WO 03/086219, WO 2010/030114, DE 10314827,JP 2004041580, WO 2010/050771, WO 2010/019001, WO 2009/157719, WO2009/145572, WO 2010/096580, DE 10314828, WO 2010/083480, U.S. Pat. No.5,599,151, EP 1 254 642, CN 101584594, CN 101732093, U.S. Pat. No.5,810,716, DE 4303311, US 2008/071208, US 2006/253109, WO 2009/095893,WO 2005/009482, CN 101637402, EP 0 621 009, WO 2009/091497, WO2006/086663, EP 2 058 090.

SUMMARY OF THE INVENTION

A first aim of the present invention is to improve the known devices andsystems.

A further aim of the present invention is to provide a mechanicalsystem, based on a new cable driven mechanical transmission, able toprovide sufficient dexterity, stiffness, speed, precision and payloadcapacity to actuate multi-DOF (degrees of freedom) micro-manipulators.Besides the possibility of being used in several articulated surgicalinstruments and robotic systems for surgery or other applicationsinvolving remote manipulation, it enables the design of a fullymechanical surgical instrument, which offers the advantages ofconventional laparoscopy (low cost, tactile feedback, high payloadcapacity) combined with the advantages of single port surgery (singleincision, scarless surgery, navigation through several quadrants of theabdominal cavity) and robotic surgery (greater degrees of freedom, shortlearning curve, high stiffness, increased intuition).

The unique design of the proposed system provides an intuitive userinterface to achieve such enhanced manoeuvrability, allowing each jointof a teleoperated slave system to be driven by controlling the positionof a mechanically connected master unit.

The design and performance specifications of this system were driven bysurgical task requirements and its use can contribute to increase theperformance of abdominal surgical procedures, increasing theirreliability.

The mechanical design of micro-mechanical systems can be performedaccording to many possible concepts and options, even if the kinematicalarchitecture has already been defined and size and shape specificationsimposed. One of the main issues is related with the design of a properactuation and transmission system. In case of micro-mechanical systemsfor minimally invasive surgery, and especially for the endoscopic units,this aspect is crucial because the working space and incision dimensionsare extremely limited and the high dexterity kinematics and demandingperformance constraints are tough design goals to be pursued, since themicro mechanisms should meet highly demanding requirements of stability,precision, force and speed to effectively perform a surgical task. Giventhat, a special effort was placed in the study and development of anovel mechanical transmission, able to meet all those specifiedrequirements.

The invention concerns a mechanism for remote manipulation comprising:

-   -   a. a plurality of movable links; and    -   b. a plurality of actuated joints placed between the said links,        in a serial, parallel or hybrid configuration; and    -   c. a plurality of joint driven pulleys, placed on each said        actuated joint, with the axis co-linear with the axis of the        respective joint, actuating different degrees of freedom of the        mechanism; and    -   d. a plurality of actuation pulleys, remotely placed relatively        to the movable links of the said mechanism        -   wherein the actuation commands are transmitted to said            driven pulleys by means of a cable driven mechanical            transmission; and    -   e. said cable driven mechanical transmission comprising a        plurality of driving cables, each coupling an actuation pulley        at a proximal location of the mechanism and another one of said        joint driven pulley, and wherein at least one of said joints is        a co-axial joint where the axis of adjoining links are aligned        or in a parallel configuration.

In an embodiment, each said driving cable may comprise a closed loopcable system, transmitting the actuation motion from the said actuationpulleys to the joint driven pulleys.

In an embodiment, each said coaxial joint(s) may comprise an idler tubewhich is coaxial with the joint axis and which is able to rotate aroundits axis.

In an embodiment, said closed loop cable may comprise a single endedcable, whose both extremities are linked to said actuated pulley or saidjoint driven idler pulley or said idler tube for transmission of thecontrolled motion by contact force.

In an embodiment, said closed loop cable may comprise two ended cables,whose extremities are attached in the said actuated pulleys, said jointdriven idler pulleys or said idler tubes.

In an embodiment, at least one of said actuated joints may be of pivottype, where the axis of the said adjoining links are not alignment andthe angle between them and changes with the movement of the actuatedjoint.

In an embodiment each said co-axial joint may comprise one joint idlertube per degree of freedom of the mechanism and each said joint idlertube are co-linear with the axis of the respective said co-axial joint.

In an embodiment, the axis of each said idler tube may keep itsco-linear position by means of a set of external ball bearings.

In an embodiment, the axial position of each said idler tube may bekept, in relation to the other idler tubes of the same co-axial joint,by means of the contact between one or more parts of the idler tube,namely radial flanges or extremities, with external ball bearings orbushing components or any other component of the mechanism.

In an embodiment, the transmission of the actuated motion between thedifferent stages of closed cable loops and the respective joint idlertubes may done through the force generated on the fixation of the cableextremities.

In an embodiment, the transmission of the actuated motion between thedifferent stages of closed loop cables, for the same said closed loopcable system, and the respective said joint idler tubes may be donethrough the contact force generated between them.

In an embodiment, said contact force may be increased by increasing thenumber of cable turns around the said joint idler tubes.

In an embodiment, said contact force may be increased by the use of achain or flexible timing belt element or any other flexible transmissionelement.

In an embodiment, the chain or flexible element may be a bead chain,comprising a cable with several spherical or other axisymmetricelements, spaced by a constant pitch, along the segments of the cablethat contact said joint idler tubes.

In an embodiment, the joint idler tubes, idler pulleys, actuationpulleys and joint driven pulleys may comprise grooves and speciallyshaped holes to hold said chain or flexible belt element and saidspherical or other axisymmetric elements, increasing the transmittedforce.

In an embodiment, the actuation pulleys may receive the input controlcommands.

In an embodiment, the input commands may be given by an operator movingdirectly the actuated pulleys.

In an embodiment, the input commands may be given by an operator movinga mechanical system that promotes the rotation of the said actuatedpulleys.

In an embodiment, the input commands may be given by a plurality ofactuators, controlled by electrical signals, to selectively drive thedistal part of the mechanism.

In an embodiment, the forces experienced by the distal part of themechanism are reproduced at the said actuated pulleys to provide forcefeedback.

In an embodiment, the invention concerns a device comprising a mechanismas defined in the different embodiments defined herein.

In an embodiment, the device is a mechanical teleoperated surgicalsystem, comprising:

-   -   a rigid support tube, having two extremities, a distal one,        which is inside the patient's body during the surgical        procedure, and a proximal one, which is located outside the        patient's body; and    -   a slave articulated unit, coupled to said distal portion of said        support tube, composed by two miniature serial manipulators,        sharing the same proximal shoulder component, said proximal        shoulder component coupled to the said distal portion of the        support tube by a rotational joint whose axis is perpendicular        to the said support tube's axis, each said miniature serial        manipulator comprising a plurality of linkages and joints and a        distal griping end-effector element;    -   a master articulated unit, placed in the distal extremity of the        said support tube, composed by two serial manipulators, each one        having a plurality of linkages and joints and a distal input        handle, with exactly the same kinematics and cable transmission        topology of the said slave manipulators, wherein input commands        from an operator cause the movement of said slave's        end-effectors according to said input commands; and    -   a cable driven mechanical transmission system, coupled between        said master and said slave manipulators, for precisely emulating        movement of said master manipulators by said slave manipulators,        wherein each driven pulley, actuating a certain degree of        freedom, of the said master manipulators is connected to the        driven pulley of the said slave manipulator actuating the same        degree of freedom; and    -   a stereoscopic image capture component positioned at the distal        end of the guide tube; and    -   distal surgical instruments, attached to the end-effectors of        the slave manipulators.

The surgical instruments may be of any type suitable to be used with thepresent invention and systems.

In an embodiment, the miniature serial manipulator has ananthropomorphic kinematics, resembling the human arm, said miniatureserial manipulator comprising:

-   -   a first distal joint, coupled to said distal end of said        proximal shoulder component, said first distal joint having a        first joint axis substantially co-axial to said proximal        shoulder component axis,    -   a first distal link movably coupled to said first distal joint,    -   a second distal joint coupled to said first distal joint via        said first distal link, said second distal joint having a second        joint axis substantially perpendicular and intersecting to said        first joint axis,    -   a second distal link movably coupled to said second distal        joint,    -   a third distal joint coupled to said second distal joint via        said second distal link, said third distal joint having a third        joint axis substantially parallel to said second joint axis,    -   a third distal link movably coupled to said third distal joint,    -   a fourth distal joint coupled to said third distal joint via        said third distal link, said fourth distal joint having a fourth        joint axis substantially perpendicular and intersecting to said        third joint axis,    -   a fourth distal link movably coupled to said fourth distal        joint,    -   a fifth distal joint coupled to said fourth distal joint via        said fourth distal link, said fifth distal joint having a fifth        joint axis substantially perpendicular and intersecting to said        fourth joint axis,    -   a fifth distal link movably coupled to said fifth distal joint,    -   a sixth distal joint coupled to said fifth distal joint via said        fifth distal link, said sixth distal joint having a sixth joint        axis substantially perpendicular and non-intersecting to said        fifth joint axis, said sixth distal joint movably coupled to        said at least one end-effector element,    -   a seventh distal joint coupled to said fifth distal joint via        said fifth distal link, said seventh distal joint having a        seventh joint axis substantially perpendicular and        non-intersecting to said fifth joint axis, said seventh distal        joint having a seventh joint axis substantially coincident to        said sixth joint axis, said seventh distal joint movably coupled        to said a second end-effector element, in such a way that said        first and second end effector elements are movable relative to,        and independently of, one another,    -   a plurality of miniaturized driving cables, each coupling an        actuation pulley at a proximal location of the support tube and        another one of said joint driven pulley, placed on said slave        distal joints; and

In an embodiment, a coupling unit, placed at the proximal end of thesupport tube, mechanically connects the said master and said slavemanipulators and their mechanical cable driven transmissions.

In an embodiment, an external manipulator mechanism, fixed relatively tothe patient, is able to provide external degrees of freedom to the saidsupport tube in such a way that the said slave unit can be inserted,positioned and moved within the abdominal cavity.

In an embodiment, said sixth distal joint has a sixth joint axissubstantially parallel to said fifth distal joint axis, said sixth jointaxis further coincident to said seventh joint axis.

In an embodiment, said sixth distal joint has a sixth joint axissubstantially perpendicular and intersecting to said fifth distal jointaxis, said sixth joint axis further coincident to said seventh jointaxis.

In an embodiment, an eighth distal joint is provided between the saidsecond distal joint and said third distal joint wherein said eighthdistal joint has a eighth joint axis substantially perpendicular andintersecting to said second distal joint axis and third joint axis.

In an embodiment, the actuation pulleys of the master and slavemanipulators are directly connected, in the said coupling unit, withmultiple transmission ratios;

In an embodiment, the positioning mechanism further comprises a setupjoint which connects the base to an operating room table or to theground.

In an embodiment, the coupling unit is adapted to releasable connect thesupport tube to the master unit.

In an embodiment, an external positioning mechanism is provided whichhas external degrees of freedom of movement that are redundant with thedegrees of freedom of movement of the said slave unit, comprises aremote centre of motion mechanism for pivoting the support tube aboutthe incision point.

In an embodiment, said input commands may comprise the operator movingat least one master manipulator input linkage, wherein movement of saidinput handle corresponds to an analogous scaled increment movement ofsaid slave end-effector.

In an embodiment, the forces experienced by the slave unit during asurgical procedure may be reproduced at the master input handle toprovide the operator with force feedback.

In an embodiment, the slave articulate manipulator comprises a seriallinkage having a number X of DOFs, and wherein said master input linkageis characterized by a number Y of DOFs where Y is equal to X.

In an embodiment, X comprises 7 slave degrees of freedom of movement andY comprises 7 master degrees of freedom of movement.

In an embodiment, X comprises 8 slave degrees of freedom of movement andY comprises 8 master degrees of freedom of movement.

In an embodiment, the rigid support tube has a free internal channel, inwhich a third surgical instrument may pass, as well as a tool toexchange the gripper distal instruments;

In an embodiment, the third surgical instrument may be flexible, havinga distal camera in the tip, or a gripping or a cutting or an ablatingend-effector.

In an embodiment, the slave manipulator unit can pivot around the distalextremity of the guide tube by the said proximal shoulder component,being inserted aligned with the tube and then, when already inside theabdominal cavity, being externally actuated to turn into a workingconfiguration, perpendicular to the said positioning tube's axis.

In an embodiment, the magnitude of movements of the slave manipulatorunit can is scaled relatively to the movements of the said mastermanipulator unit.

In an embodiment, the slave articulated unit and said master articulatedunit comprise:

-   -   a plurality of movable links; and    -   a plurality of actuated joints, placed, between the said links,        in a serial configuration; and    -   a plurality of joint driven pulleys, placed on each said        actuated joint, with the axis collinear with the axis of the        respective joint, actuating the different degrees of freedom of        the mechanism; and    -   a plurality of actuation pulleys, remotely placed relatively to        the movable links of the said articulated units and transmitting        the actuation commands to the said driven pulleys by means of a        cable driven mechanical transmission; and    -   a cable driven mechanical transmission, composed by a plurality        of driving cables, each coupling an actuation pulley at a        proximal location of the mechanism and another one of said joint        driven pulley, placed on said micro-mechanism distal joints.

In an embodiment, each of the driving cable consist of a closed loopcable system, transmitting the actuation form the said actuation pulleysto the joint driven pulleys.

In an embodiment, the closed loop cable system may be composed bymultiple sets of stages of closed loop cables, transmitting theactuation commands between them, form the said actuation pulleys to thejoint driven pulleys, and keeping a constant total length for all thepossible joint configuration of the said mechanism.

In an embodiment, the different closed loop cables of the multiple setsof stages of closed cable loops, transmit the actuation commands betweenthem by a called idler tube, comprising an axisymmetric mechanicalcomponent, able to rotate around its axis, which is aligned with theaxis of the said co-axial actuated joints.

In an embodiment, the closed loop cable is composed by a single endedcable, whose both extremities are fixed in the said actuated pulley orin the respective said joint driven pulley or in a said idler tube.

In an embodiment, the closed loop cable is composed by a single endlesscable, transmitting the controlled motion between said actuated pulleys,said joint driven pulleys and idler tubes by means of contact force.

In an embodiment, the closed loop cable is composed by two ended cables,whose extremities are fixed in both the said actuated pulley and therespective said joint driven pulley or in both the said actuated pulleyand an idler tube or in both an idler tube and a said actuated pulley.

In an embodiment, the actuated joints can be of pivot type, where theaxis of the said adjoining links are not alignment and the angle betweenthem and changes with the movement of the said actuated joint, andco-axial type, where the axis of adjoining links are aligned or in aparallel configuration.

In an embodiment, the axis of the different idler tubes, for thedifferent degrees of freedom and belonging to the same said co-axialjoint, are collinear with the axis of the respective said co-axialjoint.

In an embodiment, the axis of each said idler tube is keeps itscollinear position by means of the contact with a set of external ballbearings or bushing components or any other component of the mechanism.

In an embodiment, the axial position of each said idler tube is kept, inrelation to the other idler tubes of the same co-axial joint, by meansof the contact between one or more parts of the idler tube, namelyradial flanges or extremities, with external ball bearings or bushingcomponents or any other component of the mechanism.

In an embodiment, the transmission of the actuated motion between thedifferent stages of closed cable loops and the respective idler tubes isdone through the force generated on the fixation of cable's extremities.

In an embodiment, the transmission of the actuated motion between thedifferent stages of closed loop cables, for the same said closed loopcable system, and the respective said idler tubes is done through thecontact force generated between them.

In an embodiment, the contact force may be increased by increasing thenumber of cable turns around the said idler tubes.

In an embodiment, the contact force may be increased by the use of achain or flexible timing belt element or any other flexible transmissionelement in the dose loop cable system.

In an embodiment, the chain or flexible element is a bead chain,comprising a closed loop cable containing some spherical or otheraxisymmetric elements, spaced by a constant pitch, along the segments ofthe cable that can be in contact with the said idler tubes.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be better understood from the followingdetailed description and with reference to the drawings which show:

FIG. 1 illustrates two different architectures for remote actuated cabledriven systems, a) One actuated pulley per DOF b) Two actuated pulleysper DOF;

FIG. 2 illustrates (a) a Pivot Joint and (b) a Co-axial joint;

FIG. 3 illustrates a cable rooting along a Pivot Joint, (a) being a 2Dview and (b) being a perspective 3D view;

FIG. 4 illustrates the problem of the cable routing along a co-axialjoint;

FIG. 5 further illustrates the problem of the cable routing along aco-axial joint;

FIG. 6 illustrates a Co-axial joint Concept Development;

FIG. 7 illustrates a Co-axial joint Concept, for a 2-DOF example;

FIG. 8 illustrates a bead chain turning the idler cylinder;

FIG. 9 illustrates a use of two ball bearings to mount an idler tube;

FIG. 10 illustrates a Radial and axial restriction of the joint idlertubes;

FIG. 11 illustrates a bead chain turning the idler cylinder;

FIG. 12 illustrates a 3D Model of a micro-manipulator according to theinvention;

FIG. 13 illustrates a Kinematic Model of the micro-manipulator;

FIG. 14 illustrates cabling schematics of the 7-DOF micro-manipulator;

FIG. 15 illustrates 3D cable layout of the 7-DOF micro-manipulator;

FIG. 16 illustrates component mounting parts;

FIG. 17 illustrates radial and axial restriction of the joint turningdistal link;

FIG. 18 illustrates the overall composition of a teleoperated mechanicalsystem according to the invention;

FIG. 19 illustrates the external positioning degrees of freedom;

FIG. 20 illustrates the kinematic model of the micro-manipulatorsaccording to the present invention;

FIGS. 21 and 22 illustrate the insertion procedure for themicro-manipulators;

FIG. 23 illustrates a 3D Model of the endoscopic unit;

FIG. 24 illustrates an overview of the fully mechanical master-slavesystem;

FIG. 25 illustrates a cabling schematics of a sub-teleoperated system;

FIG. 26 illustrates a cabling schematic for the entire teleoperatedsystem according to the present invention and

FIG. 27 illustrates an overview of the entire teleoperated system withthe external positioning mechanism.

In order to actuate the joints of a micro-manipulator for MIS, two basicapproaches are possible:

(1) placing the actuators within the moving links of the manipulator, orintegrating them in the joints directly, without transmission elements;or

(2) placing the actuators on an external location, outside of thepatient's body, having the motion transmitted to each joint by means ofa complex mechanical transmission.

Internal actuation simplifies the mechanical configuration of the joint,reducing the complexity of the transmission chain. In particular, it hasthe great advantage that the motion of the joint is kinematicallyindependent with respect to other joints. However, the size of themanipulator links is imposed by the dimension of the actuators and, dueto technological power-to-volume limitations of available roboticactuation, it is quite difficult to obtain an anthropomorphic kinematicsand the required working performances and dimensions required for anendoscopic system. Furthermore, the motors occupy a rather large spaceinside the robotic structure, making it difficult to host otherelements, like different kind of sensors or internal structuralcomponents. Another issue is that, since the mass of the actuators isconcentrated inside the manipulator links, the dynamic behaviour of thesystem and its response bandwidth are reduced.

A further negative aspect is related with the routing of both power andsignal cables of the actuators. This issue is more serious for theactuation of distal joints than for the proximal ones, since the cablesin distal joints produce a relatively large resistant torque and volumedisturbance on the proximal joints.

As a consequence of all those above mentioned disadvantages, theinternal actuation of these micro-manipulators was discarded in favourof a remotely actuated solution.

As opposite to internal actuation architectures, in remote actuation thejoints are driven by actuators placed outside the moving links. Itrequires a motion transmission system, which must pass through thejoints between the motor and the actuated joint and may bring problemsof kinematic and dynamic coupling between the actuated joint and theprevious ones.

According to the type of adopted transmission elements, remote actuationsystems can be classified as (1) flexible or (2) rigid transmission.This last way of transmission is mainly based on articulated linkages orrolling conjugated profiles (e.g. gear trains) and although mayguarantee an increased stiffness of the systems, its implementation inminiature and complex multi-DOF mechanisms is extremely difficult.

On the other hand, flexible transmissions are based on deformableconnections that can adapt to variations of configuration by changingthe transmission path. They are based on flexible elements withtranslating motion, subject to tension (more frequently) or tension andcompression. Two further subcategories can be identified: pulley-routedflexible elements (tendons, chains, belts) or sheath-routed flexibleelements.

In this case, since it was aimed to develop a teleoperated mechanismwith good force reflection properties, enabling bilateral forcereflection, it was decided to use pulley-routed flexible elements,cables, with ball bearing mounted pulleys, in order to reduce the amountof friction losses along the mechanical transmission.

Remote cable driven actuation can be applied according to differenttypes of organization, depending on the number of actuated pulleys usedper joint. In particular, it is possible to recognize two main actuationarchitectures:

(1) two actuated pulleys per DOF—each one can generate a controlledmotion in one direction only and the return motion in the oppositedirection must be obtained by an external action, which can be a passive(e.g., a spring) or an active system (e.g., an antagonistic actuator);this is the case of tendon-based transmission systems;

(2) one actuated pulley per DOF—each one can generate a controlledmotion in both directions and can be used alone to drive the joint.These two architectures are illustrated in FIG. 1(a) (one actuatedpulley per DOF) and (b) (two actuated pulley per DOF).

Since the second solution requires a higher number of components andbrings additional complexity and cost to the mechanical system, thechosen architecture was the one that uses a single actuated pulley perDOF. In this case, the achievable performances are similar in bothdirections, but particular attention must be paid to backlash. Usually,it is necessary to preload the transmission system. Furthermore, theadoption of a closed loop tendon transmission requires that the overalllength of the tendon route must be kept constant, for all the possibleconfigurations of the manipulator.

Δl=0, ∀q∈W _(q)

in spite of this additional complexity, this actuation scheme has beenused, for simple applications, with only a few DOF or low dexterity.However, in a multi-DOF configuration, with high dexterity, reduceddimensions and high payload requirements, several non solved problemsarrive from the implementation of this kind of actuation transmission.

In the required kinematic design of high dexterity endoscopicmicro-manipulators, two joint configurations may be present, which canbe classified as (1) pivot joints or (2) co-axial joints, both beingillustrated in FIGS. 2(a) and (b). The distinction is related to therelative alignment of adjoining links. While in the first kind, theangle, θ_(pd), between the proximal, p, and distal, d, links changeswith the movement of the joint, see FIG. 2 a), in the co-axialconfiguration the proximal joint has an axial rotation movement inrelation to the distal one, see FIG. 2 b).

The cable routing method utilized for pivot joints is relativelystandard and can be seen in several already developed solutions. Asillustrated in FIG. 3, for this kind of configurations, the cable 2 iswrapped around a pulley 1, called the “joint idler pulley,” which isconcentric with the axis of revolution 3 of the joint. To maintain aconstant cable length, the cable 2 must remain in contact with the jointidler pulley 1 at all times. In this way, if the joint turns an angle θon the anticlockwise direction, the length of the superior segment 2′,in contact with the idler pulley, will increase and the inferior segment2″ will decrease, by the same value, Rθ, guaranteeing the constantlength of the cable closed loop. As said before, each DOF is actuated bytwo cables, wrapped around a set of two pulleys 1, passing through thejoint. The multi-DOF case, with n DOF, would require a stack of 2npulleys.

As illustrated in FIG. 3, the joint in addition comprises a set ofproximal idler pulleys 4 and a set of distal idler pulleys 5 which guidethe cable 2.

However, for the co-axial joints, the cable routing is much morecomplex. Some solutions to avoid this problem have already been proposedbut, to the best of the inventor's knowledge, not for such a smalldimension multi-DOF system with such a high dexterity and payloadrequirements. The problem consists in having an array of cables 10 beingtwisted about a co-axial axis 11, as shown in FIG. 4, when the proximallink 12 and the distal link 13 rotate relatively, with the two 10 cablesactuating the same joint being stretched in the same way, therebyincreasing the total length of the closed loop. FIG. 4 also illustratesthe proximal idler pulleys 14 and the distal idler pulleys 15.

This stretch of the different closed loops of cable 10 generates aresistant rotation moment that might be critical for multi-DOF systems.Another source of problems, as seen in FIG. 5, is the misalignment ofthe cables 10 in relation to the idler pulleys 14, identified by theangle α, caused by this twist, which may cause the disengagement of thecables from the pulleys 14 and the rubbing of the cables 10, generatingfriction and wear. These problems are especially critical on theproximal joints of the manipulators, due to the high density of cablesthat actuate the distal joints.

In some applications of micro cable driven manipulators for MIS(minimally invasive surgery), this difficulty is minimised due to thelow complexity (low number of internal DOF) of the system and the largeratio between the length of the instrument shaft, h, and the distancebetween the joint axis and the cables, d. In this way, the misalignmentof the cables in relation to the idle pulleys is almost negligible andthe change in length of the cables is small, generating a very smallresistant rotation moment. In the present case however, due to the highnumber of internal DOF and the anthropomorphic kinematic configuration,this solution may not be applied.

The developed solution for the present invention is based on the conceptshown in FIG. 3, which is adapted to be suitable for co-axial joints.More specifically, the configuration is similar but the two set ofproximal and distal idler pulleys are separated by a joint idler pulleyto allow the cables, belonging to the same closed loop, to be wrappedaround the joint idler pulley, which is now in a perpendicularconfiguration (rather than a parallel one as illustrated in theembodiment of FIG. 3), aligned with the axis of the joint.

This configuration according to the present invention is illustrated inFIG. 6. In this configuration, the crossing and rubbing of the twocables is evident (see the drawing on the left in FIG. 6) and the way toavoid it resides in dividing the single primitive closed loop in two (asillustrated in the drawing on the right in FIG. 6). By doing this, thesingle dosed loop is divided in two new closed loops, whose relativemotion is now transmitted through an axial idler pulley (or tube) seeFIG. 6.

More specifically, FIG. 6 shows (on the left side drawing) a firstintermediate configuration derived from FIG. 3. In this firstintermediate configuration, the cable 20 passes a first proximal idlerpulley 21, then over the joint idler pulley 22 (or joint idler tube), afirst distal idler pulley 23, goes to the tool to be controlled andcomes back to a second distal idler pulley 24, crosses over the jointidler pulley 22 and finally passes a second proximal idler pulley 25. Asone can easily see on the drawing of the right side of FIG. 6, the cable20 crosses over the joint idler pulley 22 which renders thisconfiguration unsuitable for the intended applications. To overcome thisproblem, the solution is illustrated in the drawing on the left side ofFIG. 6. Specifically, in this configuration, the cable 20 is dividedinto two loops 20′ and 20″ which are separated.

The first loop 20′ passes the first idler pulley 21 the over the jointidler pulley and back over the second proximal idler pulley 25. Thesecond loop 20″ passes the second distal idler pulley 24, then over theJoint idler pulley 22 and then over the first idler pulley 23.Accordingly, the motion of the first cable loop 20′ may be thentransmitted to the second cable loop 20″ via the joint idler pulley 22.

As an extension of this concept, to be able to form a multi-DOF system,the joint according to the present invention will be composed by severalco-axial idler tubes/pulleys corresponding to the pulley 22 of FIG. 6,with different lengths and different diameters, allowing the hosting ofthe different sets of proximal and distal idler pulleys for thedifferent closed loops actuating the different joints. FIG. 7illustrates the basic principle of this extension. For example, one seesin the figure the system as illustrated in FIG. 6 (drawing on the rightside) and described above (cables 20′, 20″, pulleys 21, 23, 24 and jointidler tube 22) and there is accordingly a second similar system for thesecond DOF. Specifically, basically the second system is similar to thefirst one with two cable loops 30′, 30″, proximal idler pulleys 31, 35,distal idler pulleys 33, 34 and a joint idler tube/pulley 32. Thispulley 32 has a smaller diameter than the pulley 22 and is concentricalwith this pulley 22, aligned along the same axis 11 (the joint axis).

Accordingly, this allows to have two independent actuating systems inthe same joint, and the principle may be extended further in order toadd additional DOF, the principle being to add the concentrical jointidler tubes/pulleys.

Systems with several stages of endless cables have been used in severalmechanical systems where, in order to ensure enough friction to transmitthe motion between consecutive closed loops, timing belts have beenfrequently used. However, for this specific solution, they are not asuitable choice. The main problem is related to the fact that, althoughtiming belts might be used in out-of-plane configurations, in thisreduced dimensions application, since the out-of-plane idler pulleys aretoo close to each other, this kind of configurations are not feasible.

A standard cable could be a solution. However, the friction generated bythe cable in contact with the idle pulley and/or tube, for any pair ofmaterials, wouldn't be sufficient and the wear would be excessive. Thecable could also be wrapped several times around it, with anexponentially increased friction, but it would promote an unacceptableaxial movement of the idler pulley.

Since in this configuration the motion transmission can only be madethrough half a turn of contact of cable around the joint idlertube/pulley, the friction in the contact is maximized by a speciallydeveloped bead chain, which is illustrated in FIG. 8. It is composed bya continuous stiff rope 36 (corresponding to the cables 20′, 20″, 30′,30″ described above) with several spherical beads 37, placed withconstant pitch, in the segments of the cable that may be in contact withthe joint idler tube 22, 32 as described with reference to FIGS. 6 and 7above. The bending flexibility, axial symmetry, strength and compactnessof this bead chain make it suitable for this application, where highload resistance, no slipping, low volume and right-angle driving aremajor requirements.

Wire ropes or cables are available in a variety of strengths,constructions, and coatings. Although cable strength generally increaseswith diameter, the effective minimum bend radius is decreased. Cablecompliance, cost, and construction stretch generally increases withstrand count.

During operation, the cable runs in a grooved surface 38, placed on theextremities of the idler tubes 22, 32 and the beads seat in sprocketindentations 39, where the shear force is generated.

As was already explained in the previous section, in a multi-DOFconfiguration, the primitive closed loop is divided in two new closedloops, whose motion in transmitted through the axial idler tube 22, 32,which should be able to rotate independently from other concentricalidler tubes/pulleys which are present in accordance with the embodimentillustrated in FIG. 7, while keeping its fixed axial position. Thiscould be achieved for example by the use of two internal radial ballbearings 40, in a standard configuration, as shown in FIG. 9 where thejoint idler tubes/pulleys 22, 32 correspond to the one described above.

However, in a multi-DOF system, the space gap between the concentricjoint idler tubes 22, 32 is not enough to place two ball bearings foreach idler tube and so, several (for example preferably six) miniatureexternal ball bearings may be used to guarantee the concentricity ofeach idler tube. Specifically, one uses six external bearings per jointidler tube/pulley 22, 32 to ensure a correct and stable positioning. Theaxial movement is constrained by the contact of two radial flanges withthe six bearings as illustrated in FIG. 10.

More specifically, drawing (a) in FIG. 10 illustrates an axial view ofthe arrangement of bearings 41, 42 on the joint idler tube/pulley 22,32. Drawing (b) in FIG. 10 illustrates a front view of the jointarrangement with the bearings 41, 42 and flanges 43 used to block thelateral motion of the bearings. Drawing (c) in FIG. 10 illustrates a cutand perspective view of the joint arrangement as described.

For an application example with two transmitted degrees of freedom, thelayout of the joint using the principles of the present inventiondescribed above will look like the one shown in FIG. 11. Morespecifically, this embodiment corresponds to the one illustrated in FIG.7, using the cable 36 with beads 37 and the joint idler tube 22, 32 ofFIG. 8 with the grooved surface 38, placed on the extremities of theidler tube 22, 32 and the beads seat in sprocket indentations 39.Accordingly, numerical references used in said previous figures applyhere to corresponding elements as well as the description.

Making use of the transmission concept previously proposed, the designof several novel mechanical surgical instruments can be implemented. Themain goals of these platforms are:

(1) to provide high dexterity within the abdominal cavity,

(2) to provide enough precision and stiffness, enabling the performanceof accurate surgical procedures,

(3) to have reduced dimensions and

(4) to have low inertia and friction, allowing good force reflectingproperties, increasing the transparency of the teleoperated mechanicalsystem.

As an example of application, FIG. 12 shows the overall composition of amechanical system such as a manipulator, which is able to provide thedesired dexterity to the performance of complicated surgical procedures,like pulling and cutting tissue or eventually suturing. This manipulatorhas high dexterity, high payload capacity, stiffness and precision, withseven degrees of freedom (six to orientate and to move the distalgripper, i.e. DOF1 to DOF6, and one degree of freedom, DOF7, to actuatethe gripper 50). In order to be as intuitive to control as possible, thedegrees of freedom are designed with an anthropomorphic kinematics,resembling a simplified human arm.

Achieving a kinematic model that matches the one of the human arm is achallenging task, especially in cable-driven devices, where the cablesmust be routed through joint axes while maintaining constant cablelength.

Anthropomorphic Joint approximations can be modelled at varying degreesof accuracy and complexity. The level of complexity needed for asuitable representation depends highly on the desired tasks to beperformed. For this specific system, since it is aimed to control theposition and orientation of the end-effector in the 3D space, themovement of each anthropomorphic micro-manipulator is achieved throughthe articulation of six single-axis revolute joints plus the gripper 50actuation.

The manipulator degrees of freedom are labelled from J1 to J7 (as DOF1to DOF7 illustrated in FIG. 12), from the proximal to the distal joint,in the order shown in FIG. 13.

The shoulder abduction-adduction and flexion-extension are then modelledas a composition of two intersecting axes, J₁ and J₂. The elbowflexion-extension is modelled by a single axis parallel to the secondshoulder axis, J₃. Forearm prono-supination takes place between theelbow and wrist joints as it does in the physiological mechanism, J₄,while two orthogonal joints, J₅ and J₆, represent the wristflexion-extension and radial-ulnar deviation. The offset between J₅ andJ₆ is due to the physical limitation of having two cable actuated jointswith intersecting axis. Finally, the gripper actuation is represented byJ₇ and is a result of the actuation of both gripper blades about thesame axis.

The resultant kinematics is identical to the Elbow Manipulator, which isconsidered to be the optimal kinematics for a general 6-DOF revolutejoint manipulator.

As illustrated in FIG. 13, joints J₁ and J₄ are modelled as co-axialjoints, and joints J₂, J₃, J₅, J₆, and J₇ are pivot joints.

The cabling topology of the entire manipulator using the principle ofthe present invention is schematically shown in FIG. 14 which uses theabove description of configurations of pivot joints and co-axial jointsaccording to the present invention. The design of the mechanism is suchthat the closed cable loop systems which control each degree of freedomare moved by the same actuated driven pulley placed in the external partof the body.

Pulleys M₁-M₇ actuate joints J₁-J₇ through a set of cable loops, L₁-L₇,that, depending of the degree of freedom, can have one, two or threestages, separated by the loop break lines, LB₁ and LB₂. A single cableloop runs about multiple idler pulleys, which are placed in proximal anddistal positions from the driven pulleys and joint idler tubes.

Since each idler pulley is mounted on a ball bearing in all the closedloops, with the exception of L₆ and L₇, the cables are perfectly alignedwith the idler pulleys, idler tubes and driven pulleys. In this way, theidler pulleys don't suffer any torque, which cause them to tilt about anaxis orthogonal to the pulley shaft. Since the single pulley bearingsare not designed to handle moments, tilting the pulley forces it to rubon its neighboring pulley, creating additional friction. Also, thebearings themselves are not meant to run tilted, which can create evenmore friction.

Cable loop L₁ is composed by a single loop stage, L₁₁. Starting from theactuated pulley M₁, L₁₁ engages directly the driven pulley P₁, passingby two proximal idler pulleys of joint J₁, and returns back to M₁, whereboth terminations are fixed.

Cable loop L₂ is composed by two loop stages, L₂₁ and L₂₂. Starting fromthe actuated pulley M₂, L₂₁ engages the idler tube (i.e. the joint idlertube/pulley defined above) IT₂₁, passing by two proximal idler pulleysof J₁, and returns back to M₂, where both terminations are fixed. FromIT₂₁, L₂₂ passes by two distal idler pulleys of J₁ and engages thedriven pulley P₂, where both terminations are fixed.

Cable loop L₃ is composed by two loop stages, L₃₁ and L₃₂. Starting fromthe actuated pulley M₃, L₃₁ engages the idler tube (i.e. the joint idlertube/pulley defined above) IT₃₁, passing by two proximal idler pulleysof J₁, and returns back to M₃, where both terminations are fixed. FromIT₃₁, L₃₂ passes by the two distal idler pulleys of J₁, by the idlerpulleys (proximal, joint and distal) of J₂ and engages the driven pulleyP₃, where both terminations are fixed.

Cable loop L₄ is composed by two loop stages, L₄₁ and L₄₂. Starting fromthe actuated pulley M₄, L₄₁ engages the idler tube (i.e. the Joint idlertube/pulley defined above) IT₄₁, passing by two proximal idler pulleysof J₁, and returns back to M₄, where both terminations are fixed. FromIT₄₁, L₄₂ passes by the two distal idler pulleys of J₁, by the idlerpulleys (proximal, joint and distal) of J₂ and J₃ and engages the drivenpulley P₄, where both terminations are fixed.

Cable loop L₅ is composed by three loop stages, L₅₁, L₅₂ and L₅₃.Starting from the actuated pulley M₅, L₅₁ engages the idler tube (i.e.the joint idler tube/pulley defined above) IT₅₁, passing by the twoproximal idler pulleys of J₁, and returns back to M_(s), where bothterminations are fixed. From idler tube IT₅₁, L₅₂, which is an endlessclosed loop cable stage, passes by the two distal idler pulleys of J₁,by the idler pulleys (proximal, joint and distal) of J₂ and J₃ andengages the idler tube IT₅₂. From idler tube IT₅₂, L₅₃ passes by the twodistal idler pulleys of J₄ and engages the driven pulley P₅, where bothterminations are fixed.

For each one of the degrees of freedom J₅ and J₇, the cable loops L₆ andL₇ have a single stage, L₆₁ and L₇₁. They run from the actuated pulleysM₆ and M₇ until the distal driven pulleys, P₄ and P₇, passing throughthe idler pulleys of all the proximal pivot joints of themicro-manipulator. On the other hand, when passing by the co-axialjoints J₁ and J₄, they are not passing through idler pulleys and aretwisted around the joint axis. However, due to extensive length of theloops, between the actuated and driven pulleys, and the short distancebetween the cables and the axis of rotation, the resulting stretch ofthe cables is slight, so that the resulting resistance to rotationalmotion is almost negligible. The resultant misalignment between thecables and the idler pulleys is also within reasonable limits, avoidingthe cables to jump out of their path. This twisting of the cables,however, limit the rotation of the instrument shaft to ±180″, at whichpoint the cables will rub on each other, creating friction and wear.

It is important also to note that, since the most demanding forceconstraint is on the gripping joints, L₆ and L₇ are running in anopposite phase thru the proximal joint idler pulleys, where bothcoupling torques are canceled.

The references A₁ to A₂ identify the successive joint axis.

FIG. 15 shows a 3D layout of the cabling for each 7-DOF endoscopicmicro-manipulator, related to the cabling schematics described beforewith the joints of FIG. 13.

To hold in the 3D space all the components of the cabling scheme, likeidler pulleys, ball bearings, and positioning pins and screws, specialparts were developed, guaranteeing the perfect positioning and supportof all the joint components and allowing the routing of the differentcables, considering the complex design of FIG. 15. Special attention waspaid to the assembly precision of the mechanism. Since each idler tubeis radial and axially positioned by six external miniature bearings(three on each extremity) as described here above with reference toFIGS. 10 and 11, their precise positioning is guaranteed by mountingthem on a unique base part 50, 50′, schematically illustrated in FIG.16, whose production process, for example by CNC milling machining,ensures extremely fine tolerances. Both the proximal and distal links ofa coaxial joint have a set of base parts 50, 50′, which are fixedtogether by miniature screws, having their alignment guaranteed bypositioning pins. In FIG. 16, the left side drawing shows the assembledjoint as described above previously and the right side drawing shows thejoint in the base parts 50, 50′, in a mounted state.

As explained before, the distal link has an axial rotation movement inrelation to the proximal one. Due to the lack of space, this axialrotation and the linear axial movement constraints are guaranteed by sixadditional miniature ball bearings 51, which are fixed to the distal setof base parts, in a configuration similar to the one used for the idlertubes, as illustrated in FIG. 17. In this way, the miniature ballbearings are in direct contact with an external proximal tube 52, whichis fixed to the proximal set of base parts, enabling the preciserotation of the distal set of base parts in relation to the proximal setof parts. The top drawing of FIG. 17 illustrates the joint of FIG. 16 intop view with a proximal link and a turning distal link, the bottom leftdrawing illustrates the external bearings 51 on the joint and the bottomright drawing illustrates a cut view of the joint in a tube 52.

In another aspect, the present invention relates to a mechanical systemusing the cable transmission described herein to form a teleoperatedmechanical device as will be described in detail now.

FIG. 18 gives an overview of the endoscopic unit, with two micromanipulators, whose design details were explained previously, placed inan anthropomorphic and teleoperated configuration. Specifically, FIG. 18illustrates the overall composition of this system which has a total of14 degrees of freedom (excluding a possible camera system) with a masterM, an insertion tube IT for insertion in the patient and a slave S,comprising the micromanipulators which used the cabled system describedabove.

This Surgical Platform can be divided in three major subsystems, whichare designed to work together, achieving a force reflectingteleoperation. The first one is a 14 degree of freedom micro unitcomprising two micro-manipulators, the mechanical slave 5, with ananthropomorphic kinematics, equipped with an endoscopic camera system,providing triangulation and intuitive hand-eye coordination.

The shaft S which passes into the patient's P body incision isdenominated insertion tube, IT, and not only brings the cable drivenmechanical transmission from the exterior but also provides the stablefixation and movement of the slave S unit within the abdominal cavity,see FIG. 19 that illustrates the external positioning degrees of freedomon the insertion tube IT and the slave S inside the patient P.

The 3th subsystem comprises a mechanical master interface M, which isdirectly connected to the slave S through the fully mechanical cabledriven transmission, in such a way that a surgeon's hand movements arereproduced in the slave's tip movements. In this way, the two handles ofthe master unit assume the same spatial orientation and relativeposition as the slave tips.

As compared with conventional endoscopic instruments, this mechanicalmanipulator improves the ergonomics for the surgeon, enabling apositioning of his/her hands in a natural orientation to each other,providing improved eye-hand coordination, intuitive manipulation, and anergonomic posture.

Furthermore, to optimize the manipulation performances, a surgeon hasonly to control the movements of the instrument tips, without having theneed to hold the insertion tube IT in its desired position within theabdominal cavity. Then, the insertion tube IT should be connected to anexternal positioning mechanism, linked to a fixed external reference(like ground, surgical bed, etc), which should provide the required 4DOF, see FIG. 19, to fix and move the endoscopic subsystem inside thebody of a patient P. To optimize force transmission and force feedback,the manipulators composing the master-slave system are designed to havelight weight, low inertia, high stiffness and low friction in the jointsand mechanical transmission. Finally, the endoscopic unit of the system,which enters the patient's body, is completely blo-compatible and mightbe able to be decoupled from the manipulators and sterilized.

In order to provide the desired mobility needed to perform complicatedsurgical procedures, like pulling and cutting tissue or eventuallysuturing, the internal DOFs are given by the two endoscopicmicro-manipulators 60, 61, which exhibit high dexterity, high payloadcapacity, stiffness and precision inside the patient's body. In order tobe as intuitive to control as possible, the degrees of freedom aredesigned to resemble a simplified human arm. The stereoscopic camerawill be located between the two manipulators 60, 61, providingeye-manipulator alignment similar to human eye-hand alignment, and thusenhancing the telepresence and intuitiveness of the system. This aims togive the impression to the surgeon that he/she is operating inside thepatient's body with his/her own two hands.

Anthropomorphic joint approximations can be modelled at varying degreesof accuracy and complexity. The level of complexity needed for asuitable representation depends highly on the desired tasks to beperformed. For this specific system, since we aim to control theposition and orientation of the end-effector in the 3D space, themovement of each anthropomorphic micro-manipulator 60, 61 is achievedthrough the articulation of six single-axis revolute joints plus thegripper.

The manipulator 60 degrees of freedom are labelled from 1 to 7, from theproximal to the distal joint, in the order shown in FIG. 20 whichcorresponds to FIG. 13 above and its description appliescorrespondingly.

The shoulder abduction-adduction and flexion-extension are then modelledas a composition of two intersecting axes, J1 and J2. The elbowflexion-extension is modelled by a single axis parallel to the secondshoulder axis, J3. Forearm prono-supination takes place between theelbow and wrist joints as it does in the physiological mechanism, J4,while two orthogonal joints, J5 and J6, represent the wristflexion-extension and radial-ulnar deviation. The offset between J5 andJ6 is due to the physical limitation of having two cable actuated jointswith intersecting axis. Finally, the gripper actuation is represented byJ7 and is a result of the actuation of both gripper blades about thesame axis. The resultant kinematics is identical to the ElbowManipulator, which is considered to be the optimal kinematics for ageneral 6-DOF revolute joint manipulator.

To allow the insertion of the endoscopic micro-manipulators 60, 61inside the abdominal cavity, they are first set to a strait position,aligned with the insertion tube IT axis, and then, after being insertedinside the patient's body, they are finally rotated to theiranthropomorphic working configuration, this process being illustrated inFIG. 21.

In this way, the available cross section diameter for each armmanipulator is maximized, for the same insertion tube IT diameter,specially compared with solutions where both arm manipulators areinserted at the same time, in a parallel configuration, as shown in FIG.22. With this configuration, the micro-manipulators diameter can bedoubled and their cross section magnified 4 times, enabling asignificant increasing in the achieved stiffness of the system.

FIG. 23 represents a 3D Model of the endoscopic unit 60, 61 which usesthe principles of the present invention as described above with cabletransmission and degrees of freedom (J1-J7, see the above description).

To reproduce the movements of surgeon's both hands to the correspondingmovements at the instrument grippers a fully mechanical master-slave isused, making use of the novel cable driven transmission describedbefore. An overview of the master-slave system is shown in FIG. 24comprising the master M, the insertion tube IT and the slave S, thistypically comprising the endoscopic unit illustrated in FIG. 23 andpreceding figures, as described herein.

The system comprises two sub-teleoperated systems working in parallel.In each one of those systems, an endoscopic micro-manipulator, whosedesign details were explained above, is mechanically connected toanother cable driven manipulator, with exactly the same transmissionlayout, in such a way that, when one of the systems is moved, the otherone has a corresponding movement. In other words, the joint spaces ofboth systems are equivalent:

^(N) q= ^(s) q, ∀ ^(M) q∈Wu _(q)∩^(M) q∈Wu _(q)

This feature can be achieved by directly connecting both master andslave actuated pulleys for each degree of freedom, ^(M)M_(i) and^(s)M_(i), as shown on FIG. 25 which illustrates the cabling schematicsof the system. This is similar to the system described above in relationto FIG. 14 and its description applies correspondingly. Indeed, in FIG.25, the same system is illustrated but only doubled to consider both“arms” of the manipulators 60, 61.

The cabling schematic for the entire teleoperated system is thenrepresented in FIG. 26. It corresponds to the system of FIG. 25 which isdoubled (one for the slave S and one for the master M) and thedescription made above in relation to preceding figures (in particularFIGS. 14 and 25) apply correspondingly here since the overall systemworks in an identical way.

With this teleoperated system, the ergonomics of the surgeon is visiblyimproved. He does not have to stand up with his hands in a non ergonomicposition, does not have to manipulate long endoscopic instruments withonly 4 DOFs and does not have to adapt to the mirroring effect due tothe incision in the patient's body. The surgeon can sit comfortably on achair, with supported elbows, and with his hands positioned in a naturalorientation to each other. Placing the endoscopic camera between the twomicro-manipulators, aligned with the insertion tube, together with aproperly placed of output screen, the surgeon also will be able tomanipulate his own viewing direction.

In order to be placed, fixed and moved within the abdominal cavity, theteleoperated system (master M, insertion tube IT and slave S) supportedby an external positioning manipulator 100 (see FIG. 27), which is fixedrelatively to an operating table 101, able to provide external degreesof freedom to the endoscopic micro-manipulators, in such a way that theycan be inserted, positioned and moved within the abdominal cavity of apatient.

An example of such an external positioning device 100 illustrated inFIG. 27 is given in PCT/IB2011/053576, the content of which isincorporated by reference in its entirety in the present application.

Although the present invention has been exemplified by an application ona micro-mechanism for performing minimally invasive surgical procedures,it may also be used for other forms of endoscopic surgery as well asopen surgery and also in other devices, not limited to medicalapplications.

The present mechanical system could also be employed for any suitableremote actuated application requiring a dexterous manipulator with highstiffness and quality force feedback. It can be applied in system withdifferent sizes and different kinds of remote actuations, from manual tocomputer controlled control.

Moreover, while this invention has been particularly shown and describedwith references to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention as defined by the appended claims, for example by way ofequivalent means. Also the different embodiments disclosed may becombined together according to circumstances.

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1. A method for remotely operating a teleoperated surgical device toperform a surgical procedure within an incision point at a patient'sbody, the method comprising: selecting the teleoperated surgical devicecomprising a slave unit comprising a plurality of slave linksinterconnected by a plurality of slave joints, an end-effector coupledto the slave unit, a master unit comprising a plurality of master linksinterconnected by a plurality of master joints, a handle coupled to themaster unit for operating the teleoperated surgical device, and atransmission system operatively coupled to the slave unit and the masterunit; inserting the end-effector through the incision point; and movingthe handle to transmit motion between the slave unit and master unit viathe transmission system to move the end-effector within the patient'sbody while using an external positioning mechanism to provide movementin four degrees-of-freedom about the incision point.
 2. The method ofclaim 1, wherein moving the handle in a degree-of-freedom causes thetransmission system to actuate the slave unit to move the end-effectorin a same degree-of-freedom. 3-6. (canceled)
 7. The method of claim 6,wherein the transmission system is configured such that each of theplurality of slave links of the slave unit and each of the correspondingplurality of master links of the master unit move substantially parallelto each other when operating the teleoperated surgical device.
 8. Themethod of claim 1, wherein the transmission system comprises a pluralityof actuators coupled to the plurality of slave links such that movingthe handle transmits motion between the slave unit and the master unitvia the plurality of actuators to move the end-effector within thepatient's body.
 9. The method of claim 1, wherein input commands from anoperator cause movement of the end-effector according to the inputcommands.
 10. The method of claim 8, wherein moving the handle transmitsmotion between the slave unit and the master unit via to move the endeffector in a first degree-of-freedom.
 11. The method of claim 10,wherein moving the handle transmits motion between the slave unit andthe master unit to move the end-effector in a second degree-of-freedom.12. The method of claim 11, wherein moving the handle transmits motionbetween the slave unit and the master unit to move the end-effector in athird degree-of-freedom.
 13. The method of claim 1, wherein moving thehandle transmits motion between the slave unit and the master unit tomove the end effector in seven degrees-of-freedom within the patient'sbody.
 14. The method of claim 1, wherein moving the handle transmitsmotion between the slave unit and the master unit via the transmissionsystem to move the end-effector at a predetermined selected ratiorelative to movement at the handle.
 15. (canceled)
 16. The method ofclaim 1, further comprising locking each of the slave unit and themaster unit in a stationary configuration when a surgeon is not holdingthe handle and when the device is in an active position.
 17. The methodof claim 1, wherein each of the slave unit and the master unit comprisestwo slave manipulators and two master manipulators, respectively, andwherein operating the teleoperated surgical device comprises operatingeach of the two master manipulators independently from the other. 18.The method of claim 1, further comprising positioning a user's hands onthe handle in a natural orientation to each other in an ergonomicposture.
 19. A teleoperated surgical device for performing a surgicalprocedure within an incision point at a patient's body, the devicecomprising: a slave unit comprising a plurality of slave linksinterconnected by a plurality of slave joints; an end-effector coupledto the slave unit; a master unit comprising a plurality of master linksinterconnected by a plurality of master joints; a handle coupled to themaster unit for operating the teleoperated surgical device; atransmission system operatively coupled to the plurality of slave jointsand the plurality of master joints wherein movement at the handletransmits motion between the slave unit and the master unit via thetransmission system to move the end-effector in seven degrees-of-freedomwithin the patient's body; and an external positioning mechanismconfigured to provide movement in four degrees-of-freedom about theincision point.
 20. The device of claim 19, wherein the transmissionsystem comprises a plurality of actuators coupled to the plurality ofslave links such that moving the handle transmits motion between theslave unit and the master unit via the plurality of actuators to movethe end-effector within the patient's body.
 21. The device of claim 19,wherein moving the handle in a degree-of-freedom causes the transmissionsystem to actuate the slave unit to move the end-effector in a samedegree-of-freedom.
 22. The device of claim 19, wherein input commandsfrom an operator cause movement of the end-effector according to theinput commands.
 23. The device of claim 22, wherein the input commandscomprise the operator moving the handle, and wherein movement of thehandle corresponds to an analogous scaled increment movement of theend-effector.
 24. The device of claim 19, wherein moving the handletransmits motion between the slave unit and the master unit to move theend effector in seven degrees-of-freedom within the patient's body. 25.The device of claim 19, wherein each of the slave unit and the masterunit comprises two slave manipulators and two master manipulators,respectively, and wherein each of the two master manipulators areconfigured to be operated independently from the other.